Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Beyond the readOnly and openWorld annotations, the description discloses the pricing model ($0.002 USDC per successful call via x402 on Base, Solana, or Arc) and confirms failed calls are not charged. It also clarifies scope limits by saying only models on that page are returned and specs such as range are absent.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is three tight sentences: purpose first, then scope limitations, then payment details. Every sentence contributes useful information without redundancy.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a read-only, single-parameter lookup tool with an output schema, the description covers what the agent needs: resource scope, exclusions, returned content, and payment behavior. The output schema handles return structure, so no further return-value explanation is required.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100% and the single `limit` parameter is fully documented in the schema (1–100, default 20). The description adds no additional meaning about the parameter, so the baseline of 3 is appropriate.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly identifies the resource as electric car models from the public EV Database home page and lists the returned fields (make, model name, availability text, detail URL). It does not explicitly differentiate from sibling EV or vehicle-data tools such as travel_plugshare or travel_nhtsa_vpic_vehicle_decoder, but the scope is specific enough to be actionable.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

It states an important limitation — only models on the EV Database home page are returned and specifications like range are not included — which implies when the tool is suitable. However, it does not name alternatives for range specs or charging data, nor does it give explicit when-to-use guidance versus sibling tools.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.